Android Question Lockscreen App Icon

I think it's not possible because of security issues? But it should be possible because the user downloaded the app so they trust the app to have it in his android device, or the user is already aware of what the app should do in his mobile phone.

It is possible to create a lock screen widget.

https://www.b4x.com/android/forum/threads/android-4-2-widgets.23370/#post-135520